1. Field of the Invention
The present invention relates to a gas compression feed device used when operating a small-sized microturbine power generating facility using as a fuel so-called “high humidity fuel gas” which can burn since it is mainly comprised of methane gas, but which includes a high concentration of moisture, such as the biogas generated in sewage treatment plants.
2. Description of the Related Art
In general, when using a high humidity fuel gas as the fuel of a microturbine, it is necessary to compress the high humidity fuel gas by a compressor to raise it to a pressure sufficient for use as the fuel of a turbine such as 400 kPa to 600 kPa. In the compression feed device of high humidity fuel gas used for this, normally, as shown in FIG. 2, the introduced high humidity fuel gas G1 is compressed by the gas compressor 3 and the high humidity fuel gas discharged from the compressor 3 is sent to a receiver tank 51 to make it discharge heat and thereby enable the moisture condensed and liquefied inside the high humidity fuel gas to be separated and removed by gravity. The fuel gas G5 from which moisture has generally been removed is then sent through discharge piping 10 and a discharge port 11 to the not shown microturbine. Note that the compressor 3 is provided with a cooling conduit 4 and is cooled by a heat medium such as circulating cooling water absorbing the heat of compression, but this heat is not utilized, but discharged into the atmosphere from the walls of a heat medium tank 21, the not shown radiator, etc.
At the suction side of the compressor 3, there is little change in the pressure or temperature of the high humidity fuel gas G1, so the moisture contained in the gas is difficult to liquefy, but with the high humidity fuel gas raised in pressure by the compressor 3, the moisture in the gas easily liquefies at the discharge port etc. of the compressor 3. Further, since the receiver tank 51 provided at the discharge side of the compressor 3 alone is not enough to sufficiently remove the moisture, the remaining liquid state water and gas state fuel gas and water form a mixed flow. If this is fed to the microturbine, the problem arises that the remaining liquid state water sometimes will obstruct the burning of the gas in a combustion chamber of the microturbine. Further, in cold areas, the problem sometimes arises that the remaining liquid state water will freeze in the piping from the fuel gas compression feed device to the combustion part of the turbine and block the pipes.
To solve these problems, in a compression feed device of high humidity fuel gas such as shown in FIG. 3 proposed as another prior art, instead of the receiving tank, two adsorption tanks 51a, 51b containing adsorbents are provided in parallel and switches 50a, 50b provided at their inlet sides and outlet sides are operated to alternately operate the two adsorption tanks 51a, 51b so that when adsorbing moisture at one adsorption tank, the adsorbent contained in the other adsorption tank is heated by an electrical heater etc. to separate the adsorbed moisture and regenerate the adsorbent.
Further, as another prior art, in the compression feed device of a high humidity fuel gas shown in FIG. 4, a powerful cooler 52 provided with a refrigeration machine is provided at the discharge side of the compressor 3 and the high humidity fuel gas is powerfully cooled so as to cause the moisture contained in the gas to condense and liquefy. The liquefied moisture is separated and removed from the fuel gas by a gas/liquid separator 8.
In the prior art shown in FIG. 3, however, since it is necessary to provide two adsorption tanks 51a, 51b and two switches 50a, 50b and to provide means for controlling the operation of the switches 50a, 50b, there are the problems that the capital cost and the running costs become higher and that the turbine used for frequently regenerating the adsorption tanks consumes a large amount of power. Further, in the prior art shown in FIG. 4, there are the problem that the refrigerant compressor etc. provided in the refrigeration cycle of the refrigeration machine consumes large drive power (electric power) and the problem that the facility becomes complicated and high in price. Therefore, neither method can necessarily be said to be the best.